Which carriers can I unlock from?

[Niceguy_75]

Hello,
I would like to buy a Samsung Galaxy S 2 and unlock it
What carriers can I unlock from?

 

[splatman213]

usually only gsm carriers, which in the u.s would be att and tmobile. Abrad it would be any carrier that uses sim cards

 

[Niceguy_75]

Right

ATT gave me the unlock code on my new so I could switch carriers

Thanks